1. Field of the Invention
This invention relates to energy saving devices, and more particularly to a system for recovering waste heat from flue gasses leaving a chimney through the implementation of a recovery exchanger, for storing the recovered heat in a reservoir, and further for controllably rejecting the recovered heat to the interior of the building. It is anticipated that the primary application for the invention disclosed herein will be as a supplemental residential heating unit.
2. Description of the Prior Art
In the past, the climbing cost of energy has presented a problem, which problem has been particularly acute for such essential applications as domestic heating. Often, homes were provided with fireplaces, but the use of the conventional fireplace typically represented a net heat loss, in that heated air from the conditioned space of the building was utilized for combustion and subsequently escaped up the chimney. While heated air was escaping up the chimney, unheated make-up air correspondingly migrated into the conditioned space.
Various attempts have been made to develop a workable low cost heat recovery system to gainfully utilize the heat which normally had escaped from the chimney. In U.S. Patent No. 2,355,495 to Zier on August 8, 1944, a system is disclosed which jackets the chimney and combustion source to recover heat. However, the disclosed apparatus is not readily adaptable to an existing fireplace and chimney, in that extensive structural modifications would be required for installation.
In U.S. Pat. No. 4,158,439 to Gibbs on June 10, 1979, a waste heat collector is disclosed which includes elongated ducts to be suspended within a chimney to effect the heat recovery with a working fluid circulating through the ducts. However, the specification therein acknowledges a problem in that where a low cost working fluid (e.g. water) is utilized a possible freezeup of the working fluid is possible when the combustion source is not in operation. The recommended solution is to utilize a more expensive anti-freeze liquid as the working fluid.
In U.S. Pat. No. 4,160,524 to Stiber on July 10, 1979, another waste heat recovery system is disclosed, but as in the Zier U.S. Pat. No. 2,355,495, requires extensive, expensive structural modification to the building where the system is to be installed on an existing fireplace.
A need continued to exist for a waste heat recovery system readily adaptable to an existing fireplace equipped structure, which system required only minimal structural modifications to the standing building for installation, which system was protected against a freeze-up of the working fluid within the system, and which system was selectively operable to store a quantity of heat for subsequent transfer to the condition space of the structure.
This application is a continuation in part of copending applications U.S. Ser. No. 235,008 titled "Apparatus for and Method of Recovering Chimney Heat", filed Feb. 21, 1981.